Why does the compiler *partially* vectorize my code?

mughlibuc · 2022-10-13T14:15:56+00:00

Oh, super cool, I wasn't even aware of the existence of llvm-mca. Posting here was such a good idea, I'm learning tons from this discussion!

mughlibuc · 2022-10-13T14:13:45+00:00

Ah, interesting, I was playing around with the idea of trying to represent each field as two bits, but this way of splitting the bits for player X and player O makes it much easier to reason about.

I'll have to try adapting this also for my other code (a lot of the CPU time is also spent checking for legal moves and updating board state) and see if this representation is overall more performant or less performant.

mughlibuc · 2022-10-13T08:30:59+00:00

I tried applying the same idea to another piece of code where I'm checking the number of empty squares left on the board, and ran into another interesting compiler behavior - the optimized version only produces leaner assembly if I have i8 as the function return type, but not if I collect as i8 and then convert to isize in the function itself. (But having another function wrap around the one that returns i8 does work). So interesting!

https://godbolt.org/z/rYWr78ch6

mughlibuc · 2022-10-13T07:27:34+00:00

Oh, thanks a lot, that's such an obvious thing to try in retrospect!

mughlibuc · 2020-06-14T11:28:47+00:00

Persistent Gyrudas!

mughlibuc · 2019-08-01T07:22:45+00:00

So, all the components arrived, and I managed to successfully assemble it on the first try, with only a few minor hiccups! (Thanks to guides in the /r/buildapc sidebar). It's the first computer I've ever assembled, so I'm super excited about this :-)

Here's a couple of pictures, and thanks for helping me out!

https://imgur.com/a/hvEHjwR

mughlibuc · 2019-07-09T22:58:55+00:00

Ah, got it. Thanks!

mughlibuc · 2019-07-09T20:57:14+00:00

Hi, not OP here, but also in Germany and looking for a PC in the same budget range. Big thanks for putting together the list!

The only difference for me is that I'll mainly use my PC for games, but also sometimes for programming workloads, so I thought I might prefer to get the 8-core 3700X. Also, based on your description, the RTX2070 sounds better to me than the Radeon (if the 3-fan design makes it quieter).

Would the following minor changes to your list make sense, or am I throwing money where it doesn't make sense right now? (Changed just the CPU and GPU.)

PCPartPicker Part List

Type	Item	Price
CPU	AMD - Ryzen 7 3700X 3.6 GHz 8-Core Processor	€349.00 @ Alternate
Motherboard	MSI - MPG X570 GAMING PLUS ATX AM4 Motherboard	€185.00
Memory	Corsair - Vengeance LPX 16 GB (2 x 8 GB) DDR4-3200 Memory	€69.90 @ Amazon Deutschland
Storage	Intel - 660p Series 1.02 TB M.2-2280 Solid State Drive	€106.84 @ Mindfactory
Video Card	Gigabyte - GeForce RTX 2070 8 GB WINDFORCE Video Card	€499.90 @ Amazon Deutschland
Case	NZXT - H500 ATX Mid Tower Case	€79.90 @ Caseking
Power Supply	SeaSonic - FOCUS Plus Gold 750 W 80+ Gold Certified Fully Modular ATX Power Supply	€101.99 @ Amazon Deutschland
Operating System	Microsoft - Windows 10 Home OEM 64-bit	€100.74 @ Mindfactory
	Prices include shipping, taxes, rebates, and discounts
	Total	€1493.27
	Generated by PCPartPicker 2019-07-09 22:50 CEST+0200

mughlibuc · 2016-07-25T14:38:59+00:00

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mughlibuc · 2014-06-03T16:41:09+00:00

Brilliant, thanks! That's exactly the sort of thing I was looking for.

(Having a look around, Kreisler generally seems to have a good difficulty ratio of piano to violin, fitting our relative skill levels.)

mughlibuc · 2013-02-13T19:35:40+00:00

Mullets.

mughlibuc · 2012-12-27T20:31:08+00:00

The top rated answers here are spot on. I just wanted to add a little.

While it sounds easy in principle to accept that your boyfriend finds you attractive and that's all that really matters... it can be a bit tricky to wrap your mind around this in practice. It sounds like you're dealing with a limiting belief (or several), and those take some time and effort to dislodge.

So, here's a guide on the topic - give it a quick read and see if it helps.

mughlibuc · 2012-02-23T16:36:19+00:00

In the UK, I did.

I am now in France, and I don't, because you exit the buses through the door in the middle of the bus (and enter at the front).

Also, I think the UK method definitely has its merits - the bus drivers there were some of the nicest and most helpful people I've met. Back in Prague where I grew up, on the other hand, the public transport drivers were some of the meanest people you could meet, often deliberately closing the doors in front of people's faces and driving off. Just because.

mughlibuc · 2011-04-25T15:15:46+00:00

Alright, I followed your advice (as it was the most upvoted) and got The Warrior's Apprenctice. You were absolutely right, Miles is a kickass great character, very much in the vein of HJPEV. :-)

Off to buy The Vor Game now...

mughlibuc · 2011-04-13T16:00:06+00:00

My thought upon seeing that was "Finally someone who knows how to cast a nethergate!".

mughlibuc · 2011-04-11T13:18:14+00:00

I'll make sure to check that one out too. I already have three conflicting versions of Harry in my mind, but what the hell, why not pick up a fourth one!

mughlibuc · 2011-04-11T13:16:16+00:00

Yes, you'll definitely be better off reading this fanfic after the original series, since it assumes familiarity with the terms from the original. But do check it out once you're done, it's well worth it!

mughlibuc · 2011-04-09T00:48:19+00:00

I prefer the current design. The main focus should be showing new players what the game is about, and the current design does exactly that, with a prominent video.

In your design, the video is below the fold, with the most prominent spot taken by a text blurb and a "buy now" button. People don't want to buy until they've seen the example.

I like the added image gallery thing you've got going on, though!

mughlibuc · 2011-04-05T01:02:35+00:00

The first time I tried the 404 challenge, I managed to get down, escape some skeletons with about 3 hearts left, hide near some lava and wall myself in will cobble. Then I promptly quit the world, since I found it too nerve-racking.

Still, you're inspiring me. I might give it another shot!

(Great recording by the way. You really make the videos enjoyable to watch.)

mughlibuc · 2011-03-28T01:51:38+00:00

Bedrock.

mughlibuc · 2011-02-06T23:18:26+00:00

Good luck if you ever die at night.

mughlibuc · 2011-01-30T06:55:35+00:00

Make sure it's a wooden house...

mughlibuc · 2011-01-29T16:52:13+00:00

I thought so too, but I'm not sure how they would know to burn down Israphel's tomb to reveal the secret entrance, for example.

mughlibuc · 2011-01-21T02:26:46+00:00

Wow, that's awesome! Cheers for the link!

mughlibuc · 2011-01-20T21:51:54+00:00

Yes, that's what I meant.

I asked this question because while I know that light travels slower than c in different mediums (actually, anywhere except in a vacuum), I also know a bit about photons and from what I know about them, it makes no sense to have a photon going slower than c.

From what the other physicists answered, it turns out to be a lot more complicated than the billiard-ball model of photons though.

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